The Developing Person Through Childhood and Adolescence by Kathleen Stassen Berger Seventh Edition Chapter 5 The First Two Years: Biosocial Development Slides prepared by Kate Byerwalter, Ph.D., Grand Rapids Community College
Body Changes • An average newborn is 7½ lbs, 20 inches. • Infants triple their birthweight by 1 year. • By age two, they are about ½ their adult height (!) and ¼ their adult weight.
Body Changes ALL: INES YVETTE LARAYA ERESE
Body Changes (cont.) • Percentile ranks: allow comparisons of an individual infant to group norms • A sudden drop in percentile rank might indicate a developmental problem. • Head Sparing: in cases of inadequate nutrition, the brain keeps growing
The Wonderful World of SLEEP • Newborns sleep 17+ hours a day. DAVID YOUNG-WOLFF / PHOTOEDIT, INC.
Infant Sleep (cont.) • Infants gradually adjust to the family’s sleep schedule. • 80% of 1 year olds sleep “through the night” • Sleep cycles are influenced by brain maturation, diet, child-rearing practices, and birth order
Make It Real: Co-Sleeping • Some families practice “co-sleeping,” in which the family shares a bed. • Why might a family do this? Do you think it could benefit or harm an infant?
Research on Co-Sleeping • CULTURE influences the decision (it is more common in Eastern culture) • It is not harmful to an infant, under normal circumstances (e.g., if adult is not drunk) • It may increase dependence on parents
Brain Development • Brain development during infancy is fascinating and rapid. • By the age of 2, the brain is 75% its adult weight • Neural connections in the brain also develop
Brain Development (cont.) • Regional specialization: neurons in certain areas of the brain correspond to different tasks • Examples: language, vision, smell, emotional processing, recognizing faces vs. objects, etc.
Brain Development (cont.) • Transient exuberance: rapid proliferation of new neural connections in infancy • As many as 15,000 new connections per neuron and 100 trillion synapses by age 2! • Pruning makes the brain more efficient by eliminating underused connections.
What influences early brain development? • Brain development is influenced by maturation and experiences. • Experience-expectant brain functions require basic common experiences. • Example: No matter where an infant lives, he or she hears sounds and language.
What influences early brain development? (cont.) • Experience-dependent brain functions depend on exposure to particular events. • Example: The particular sounds and language heard (and learned) varies across infants. • Example: The development of impulse control depends on both maturation and practice.
Why are neural connections so important? • A certain level of neural connections indicate healthy brain development. • Lack of connections may result from child abuse or neglect early in life, and can have lasting consequences. • Example: Infants in orphanages
Make it Real: Activities • Make a list of toys and activities that can stimulate healthy brain development in the first two years of life. PHOTODISC
Implications for Caregivers • Is it possible to overstimulate an infant? YES! • The key is to follow the infant’s lead • Self-righting: an infant’s inborn drive to use whatever experiences available to develop the brain (wow!)
Infant Senses • All five senses function at birth • Vision, hearing, taste, touch, smell • Perception (the brain’s processing of the sensation) develops over time.
Infant Senses (cont.) • Hearing: is well developed at birth • Infants respond to sudden noises, human voice, phonemes of language • Vision: is the least mature sense at birth • Bionocular vision develops around 14 weeks • “Adult” vision (20/20) by one year
Infant Senses (cont.) • Taste, touch, smell function well at birth All: CINDY CHARLES / PHOTOEDIT, INC.
Motor Skills • Motor skills develop according to two principles: • Cephalocaudal: growth proceeds from head-to-toe (e.g., head lift before sit, stand, walk) • Proximal-distal: growth proceeds from torso outward (e.g., sucking before kicking)
Motor Skills (cont.) • Reflexes account for the first motor skills. • Survival reflexes include sucking, breathing, body temperature. • Other reflexes include the Babinski, Moro, and stepping reflexes.
Infant Reflexes ASTIER / BSIP / SCIENCE SOURCE / PHOTO RESEARCHERS, INC. JENNY WOODCOCK; REFLECTIONS PHOTOLIBRARY / CORBIS PETIT FORMAT / PHOTO RESEARCHERS, INC.
Make it Real: Motor Skills • At what age do you think most infants learn to walk? • What about you? PHOTODISC
Motor Skills (cont.) • Gross motor skills involve large muscle movements. • Examples: crawling, sitting, walking • Walking typically occurs around 12 months, with great variability across infants. • Walking requires muscle strength, brain maturation, and practice.
Motor Skills (cont.) • Fine motor skills involve small muscle movements. • Examples: learning to grasp, shake, pull an object, hold a spoon, write, draw, etc. • Motor skills are influenced by genes, culture, and patterns of infant care.
Public Health Measures • Infant survival rates have increased significantly in the past century, due to better nutrition, cleaner water, and immunization. • Although not without controversy, immunization has been hailed as a major achievement (e.g., significantly reducing polio, small pox, measles).
Sudden Infant Death Syndrome • SIDS is infant death of an unknown cause. • Protective factors (although not a guarantee) include: NO cigarette smoke in house, noise and touch during sleep, breast feeding, sleeping on back